Gas powered turbines utilize a compressor to compress air. The compressed air is provided to a combustor, where the compressed air is mixed with a fuel and ignited. Combustion gasses resulting from the ignition are expelled from the combustor into a turbine section. The combustion gasses expand as they pass through the turbine section, driving the turbine section to rotate. The turbine section is coupled to at least one shaft and drives rotation of another component. In a gas turbine engine for an aircraft, the shaft drives rotation of a fan. In a land based turbine system, the shaft is an output shaft driving another component, such as an electric generator.
The compressor portion includes multiple sequential stages that use rotors to drive air through the compressor and compress the air. Rotation of the compressor combined with the air passing through the compressor can cause the rotors within a stage to enter a stiff wise bending mode. The stiff wise bending mode causes the blade of the rotor to rock along a chord line, with the chord line being defined by the blade. The vibrations from the rocking can lead to rotor rim bending and can damage the rotor.